Carrier HVAC Error Code 24: How to Fix It

Medium 30-60 minutes Medium Severity Verified June 2026
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Error Code
24
Brand
Carrier
Product Type
hvac
Severity
Medium
DIY Difficulty
Medium
Estimated Fix Time
30-60 minutes
Carrier HVAC error code 24 indicates that the secondary voltage fuse on the control board has blown. This usually happens due to a short circuit or overcurrent in the low-voltage wiring, such as a damaged thermostat wire or a faulty component. Fixing it involves replacing the fuse and addressing the underlying cause.
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Tools You'll Need

How to Fix Error Code 24

  1. Turn Off Power

    Always disconnect power before working on electrical components.

  2. Locate the Control Board

  3. Inspect and Remove the Blown Fuse

  4. Replace with Correct Fuse

    Using the wrong fuse rating can cause further damage or fire.

  5. Check for Short Circuits

  6. Restore Power and Test

Parts You May Need

3-amp 250V AGC fuse
Check Price on Amazon
3-amp 250V AGC fuse
Check Price on Amazon
3-amp 250V AGC fuse
Check Price on Amazon
3-amp 250V AGC fuse
Check Price on Amazon
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When to Call a Professional

If the new fuse blows immediately or if you suspect a short in the compressor, blower motor, or control board, call a licensed HVAC technician. Repeated fuse failures may indicate a deeper electrical issue.

Frequently Asked Questions

What does Carrier error code 24 mean?
It means the secondary voltage fuse on the control board is open (blown), usually due to a low-voltage short circuit.
Can I reset Carrier error code 24?
No, resetting only clears the code temporarily. You must replace the blown fuse and fix the underlying short circuit.
What causes a fuse to blow in a Carrier HVAC system?
Common causes include a shorted thermostat wire, a faulty contactor or transformer, moisture ingress, or a damaged control board.
What size fuse does a Carrier furnace use?
Most Carrier units use a 3-amp or 5-amp, 250V AGC or MDL fuse. Check your unit's manual or fuse label.
How much does it cost to fix Carrier error code 24?
DIY cost is around $5 for a fuse. Professional service can cost $100-$300, including diagnostics and repair.

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